The Pattern Speeds of NGC 3031, NGC 2366, and DDO 154 as Functions of Radius

The pattern speeds of NGC 3031, NGC 2366, and DDO 154 are measured using a solution of the Tremaine-Weinberg equations derived in a previous paper. Four different data sets of NGC 3031 produce consistent results despite differences in angular resolution, spectral resolution, and sensitivities to structures on different scales. The results for NGC 3031 show that the pattern speed is more similar to the material speed than it is to the speed of a rigidly rotating pattern, and that there are no clear indications of unique corotation or Lindblad resonances. Unlike NGC 3031, the results for NGC 2366 and DDO 154 show clear departures from the material speed. The results for NGC 2366 and DDO 154 also show that the solution method can produce meaningful results that are simple to interpret even if there is not a coherent or well-defined pattern in the data. The angular resolution of a data set has the greatest affect on the results, especially for determining the radial behavior of the pattern speed, and whether there is a single, global pattern speed.Comment: Accepted for publication in The Astrophysical Journa

Wintering Yellow-Bellied Sapsucker Time Activity Budgets in East Texas Bottomland Hardwood Forests (Abstract)

We developed time-activity budgets for 286 Yellow-bellied Sapsuckers (Sphyrapicus varius) from October 2005/2006 to March 2006/2007 in east Texas bottomland hardwood forests. Behaviors were similar between genders and study sites (P \u3e 0.05), but varied (P = 0.008) between years. Sapsuckers spent more time foraging upon arrival in wintering areas and during morning throughout the study periods. Deviation from monthly average low temperature was an important (P = 0.038) covariate during the second study year, when sapsuckers increased time spent foraging during colder than average temperatures and increased time perching on days with warmer than average temperatures. Sapsuckers partitioned about half their time foraging (early in the day) and half their time perching (later in the day). Sapsuckers may have little physiological need for drastic behavioral adjustments to successfully meet nutritional demands during winter in areas with mild climates

The Shearing HI Spiral Pattern of NGC 1365

The Tremaine-Weinberg equations are solved for a pattern speed that is allowed to vary with radius. The solution method transforms an integral equation for the pattern speed to a least squares problem with well established procedures for statistical analysis. The method applied to the HI spiral pattern of the barred, grand-design galaxy NGC 1365 produced convincing evidence for a radial dependence in the pattern speed. The pattern speed behaves approximately as 1/r, and is very similar to the material speed. There are no clear indications of corotation or Lindblad resonances. Tests show that the results are not selection biased, and that the method is not measuring the material speed. Other methods of solving the Tremaine-Weinberg equations for shearing patterns were found to produce results in agreement with those obtained using the current method. Previous estimates that relied on the assumptions of the density-wave interpretation of spiral structure are inconsistent with the results obtained using the current method. The results are consistent with spiral structure theories that allow for shearing patterns, and contradict fundamental assumptions in the density-wave interpretation that are often used for finding spiral arm pattern speeds. The spiral pattern is winding on a characteristic timescale of ~ 500 Myrs.Comment: Accepted for publication in The Astrophysical Journa

Habitat and Host Tree Selection by Wintering Yellow-bellied Sapsuckers in East Texas

Yellow-bellied Sapsucker (Sphyrapicus varius) foraging ecology has long been a focus of study, primarily due to their sap-foraging behavior throughout the year and speculation on how sapsuckers subsist by foraging on dormant host trees during winter. Wintering sapsucker habitat use as related to host tree selection is not clearly defined, particularly in the southwestern portion of its range. We studied Yellow-belliedSapsucker habitat use and host tree selection in two bottomland hardwood forest sites in eastern Texas during winters, 2005–2006 and 2006–2007. Habitat surrounding overcup oak (Quercus lyrata) host trees was generally characterized by fewer trees/ha, lower species diversity and richness, and taller trees than random plots. Overcup oak host trees tended to be healthier than overcup oak non-host trees, but host trees had thinner, less complex bark than non-host trees, irrespective of tree size and health. Also, digestible cell and protein content was similar between host and non-host trees, irrespective of tree size and health. Selection of host trees with thinner, less complex bark suggest sapsuckers use visual cues to focus host selection upon bark morphology and evidence of previous use. Combined, wintering sapsuckers may increase foraging efficiency and maximize caloric intake by increasing energy gained/unit time foraging on already established, and presumably productive host trees. Despite similarities in habitat, health and cell and protein content between host and non-host trees, Yellow-bellied Sapsuckers selected healthy host trees with thin, less complex bark where stable levels of digestible cell content and protein over time provide a reliable, consistent food source throughout winter